Prevalence and transmission potential of Borrelia burgdorferi in three species of wildcaught Plestiodon spp. skinks of the southeastern United States

In the southeastern United States, blue-tailed skinks (Plestiodon spp.) are important hosts for Ixodes scapularis ticks, the principal vector of Lyme disease (LD) in this region. Skinks and other southeastern lizards are not thought to be reservoir competent for Borrelia burgdorferi sensu stricto (Bbss), the etiological agent of LD in the United States. . Lizard-feeding by southeastern I. scapularis may tend to suppress sylvatic cycles of B. burgdorferi, and thus may be an important reason why LD case rates in the Southeast are much lower than in the Northeast and upper Midwest. Nevertheless, some skinks in Florida and South Carolina have tested positive for Borrelia spp. bacteria. The aims of this project therefore were the following: i) to determine the natural prevalence of Bbss in Plestiodon spp. skinks from the Southeast; and ii) to determine whether or not skinks experimentally infested with Bbss-infected I. scapularis would become a source of Bbss infection for naive ticks. Forty skinks were caught in southeastern states, of which two (5%) tested positive for a Borrelia species (not Bbss). In the laboratory, 25 uninfected skinks were infested with Bbss-infected nymph I. scapularis. Bbss infection in laboratory-infected nymphs declined from 72% before feeding to 7% after feeding on these skinks, suggesting this feeding had a strong zooprophylactic effect. Only one skink subsequently transmitted Bbss to a single xenodiagnostic larva, and that infection was transient. In contrast, all infected positive control mice transmitted infection to multiple larvae for the duration of the 6-week study. Skinks in the Southeast are probably not an ecologically-significant wildlife reservoir of Bbss, and are not contributing directly to the LD cycle. The prevalence of other Borrelia species in skinks, and the possibility that such bacteria could be acquired and transmitted by human-biting ticks, remains an avenue for further study.